Valve arrangement

ABSTRACT

A valve arrangement for a pressure fluid, particularly high-pressure oil, has a valve housing (10, 90, 190) with an internal, cylindrical sealing surface (16, 100, 160) which forms a guide for the outer, cylindrical sealing surface (42, 107, 162) of a piston body (18, 106, 138). There is provided a circular groove which accommodates a sealing ring (46, 64, 108, 164). An axially displaceable valve sleeve (30, 70, 122, 156) is disposed coaxially with the two cylindrical sealing surfaces(16, 42, 100, 107, 162, 160) and has a cylindrical valve-sealing surface (40, 74, 124, 158). This valve sleeve is biased by a spring (34, 80, 118, 172) such that one end (36, 82, 126, 174) abuts substantially sealingly a seating (38, 86, 128, 176) at that end of the sealing surface such as to form a closed gap (41, 86, 130, 178) at one end of a channel (32, 73, 132, 145). The valve housing (10, 90, 190) is displaceable axially from a starting position relative to the piston body (18, 106, 138) to an intermediate position in which the sealing ring (46, 64, 108, 164) has been moved from a position on one side of the closed (41, 86, 130, 178) to a position on the other side of the closed gap.

The present invention relates to a valve arrangement intended forpressure fluids, such as high-pressure oil, and being of the kind setforth in the preamble of the following claim 1.

Such valve arrangements are incorporated, inter alia, in quick-couplingsof the kind which comprise a male part which can be pushed into a femalepart, so as to connect together two conduits or passageways. The valvearrangement may also be included in a hydraulic valve operative to openand close the connection between two conduits or passageways.

The valve arrangements include an elastic or resilient sealing ringwhich is fitted in a circular groove and which is subject to the effectof high-pressure fluid on one side thereof. The valve arrangement mayalso include a further sealing ring, which may be subject to the effectof high-pressure fluid, low-pressure fluid or atmospheric pressure onthe other side thereof. By high-pressure fluid is normally meanthigh-pressure oil having a pressure of at least 10 bars and in thosecases to which the invention pertains generally a pressure of at leastsome hundred bars.

When such a valve is opened, the high-pressure fluid will flow throughthe valve in an explosive, violent fashion for a short period of timeand will strike the elastic sealing ring in such a manner that the ringwould be torn from its groove unless precautionary measures are taken toprevent this from happening. These precautionary measures normallyinvolve the incorporation of a solenoid valve in the conduit upstream ofthe valve arrangement, this solenoid valve being kept closed when thevalve arrangement is adjusted from a closed to an open valve-setting andthe sealing ring is moved through the risk zone. Only then is thesolenoid valve opened, so as to allow the high-pressure oil, or otherhigh-pressure fluid, to pass through the valve without damaging thesealing ring. The provision of the solenoid valve, or any other kind ofclosing valve, however, adds to the manufacturing costs and complicatesmanipulation of the valve arrangement. Furthermore, the presence of theadditional closing valve considerably prolongs the time taken to openthe valve arrangement.

Consequently, an object of the present invention is to provide a valvearrangement of the aforesaid kind which can be opened without the aid ofadditional closing valves.

The invention is intended primarily to improve quick-couplings intendedfor connecting a pressure-oil source having a pressure of severalhundred bars to a hydraulic tool, and then particularly toquick-couplings of the kind in which a number of male coupling-parts areattached to a carrier plate which can be moved hydraulically, backwardsand forwards in relation to stationarily mounted female coupling-partsintended to receive respective male parts upon forward coupling-movementof the carrier plate. In these instances it is unnecessary to providethe female coupling-parts with locking sleeves which coacts with ballssuch as to lock the male part to the female part when coupling the twoparts manually together at a relatively low pressure in a conventionalmanner. However, the invention is also intended for application inquick-couplings where the fluid pressure is sufficiently low to enablethe male and female parts to be coupled manually, such as in the case ofvarious types of hydraulic tools which operate at a hydraulic pressureof about 10 bars or less.

The improved, inventive valve arrangement of the aforesaid kind has thecharacteristic features set forth in the characterizing clause of thefollowing claim 1.

Thus, the elastic sealing ring is protected by an axially displaceablevalve sleeve which holds the throughflow passageway closed until thesealing ring has been moved to a safe position, whereafter displacementof the valve sleeve opens the throughflow passageway.

These and other details and advantages significant of the invention aredescribed below in more detail with reference to a number ofexemplifying embodiments of an inventive valve arrangement illustratedin the accompanying drawings.

FIGS. 1 to 3 are mutually similar axial-sectional views of a hydraulicclosing valve which incorporates an inventive valve arrangement, andshow respectively the valve in a closed position, an intermediateposition and an open position.

FIG. 4 is an axial sectional view of the male part of a quick-couplingincorporating an inventive valve arrangement and shows the valve in itsclosed position.

FIG. 4a shows the valve arrangement of FIG. 4 in its open position.

FIG. 5 is an axial sectional view of the female part of a quick-couplingincorporating an inventive valve arrangement, and shows the valvearrangement in its closed position, the illustrated female part beingable to receive the male part shown in FIG. 4.

FIG. 5a shows the valve arrangement of FIG. 5 in its open position.

FIG. 6 illustrates the male part of FIG. 4 inserted partially in thefemale part of FIG. 5, such as to occupy an intermediate position inwhich the valve arrangements of the two coupling parts are still closed.

FIG. 7 illustrates a subsequent intermediate position in which the twosealing rings are still located in a position in which they areprotected by respective valve sleeves, with the valve arrangements stillclosed.

FIG. 8 illustrates the coupling of FIG. 7 in a fully coupled position,with both of the valve arrangements being fully open.

FIG. 9 illustrates a modified version of the male part shown in FIG. 4.

FIG. 10 illustrates a modified version of the female part shown in FIG.5, this female part fitting into the male part shown in FIG. 10.

FIG. 11 illustrates the male part of FIG. 9 and the female part of FIG.10 in their coupled state.

FIGS. 12 and 13 illustrate respectively a male coupling-part and afemale coupling-part which correspond essentially with the male andfemale coupling-parts shown in FIG. 4 and FIG. 5 respectively, but withthe difference that the female part is not provided with the inventivevalve arrangement, since said female part is not connected to ahigh-pressure conduit. Furthermore, the male and female parts can belocked together with the aid of a conventional ball catch.

FIG. 14 illustrates the coupling parts of FIGS. 12 and 13 in theirmutually coupled and locked position.

The simplest embodiment of the inventive valve arrangement isillustrated in conjunction with the hydraulic valve illustrated in FIGS.1-3, this valve having two inventive valve arrangements.

The hydraulic valve illustrated in FIG. 1 includes a valve housing 10 inwhich there is included a passage through which oil under high pressurecan flow when the valve arrangements are open. The ends of the passageare provided with respective connections 12 and 14 for connection toconduits not shown.

Along part of its length, the passage is configured to present aninternal, cylindrical sealing surface, such as to form a cylinder 16. Apiston body 18 is mounted for axial movement in said cylinder.

The hydraulic valve of the illustrated embodiment includes two inventivevalve arrangements which enable high-pressure oil to be connectedalternatively to the connection 12 or the connection 14.

The respective ends of the cylinder 16 adjoin two widened passage-partswhich have conical end surfaces 20 and 22 and each of which forms arespective pressure chamber 24 and 26.

A valve body 28 having a valve sleeve 30 and axially extending channels32 is mounted for axial movement in the chamber 24. The valve body isbiased towards the end surface 20 by a stronger compression spring 34, aconical end 36 of the valve sleeve being in abutment with a seating 38located at the inwardly located part of the end surface 20. The contactbetween said end of the valve sleeve and said seating is ametal-on-metal contact and forms a corresponding seal with a givenminimum leakage.

The seating and the valve sleeve may have mutually the same conicity,although in the case of the illustrated embodiment the seating and valvesleeve have mutually different conicities, such as to obtain a smallabutment surface which lies in the proximity of the sealing surface 40,thereby decreasing the hydraulic forces which counteract opening of thevalve sleeve. This embodiment is intended for extremely high pressuresin the chamber 24. The inner surface of the valve sleeve 30 forms aninternal, cylindrical sealing surface 40 which is an interruptedextension of the cylindrical sealing surface of the cylinder 16.

Defined between the conical end 36 and the seating 38 is a gap which isclosed in the illustrations of FIGS. 1 and 2, and is referenced 41 inthis closed state. The gap is referenced 41A in its open state orposition, shown in FIG. 3. The external, cylindrical sealing surface 42of the piston body 18 has provided therein a circular groove 44 whichaccommodates a substantially elastic sealing ring 46 which in FIG. 1abuts the internal, cylindrical sealing surface 16 in a manner toprovide an effective seal and prevent leakage past the sealing ring.

The piston body 18 is manouvered by means of a piston rod 48 attached toone end of the piston body. The other end of the piston body is extendedwith a pin 50. When the piston body is displaced in the direction of thearrow 52 relative to the valve housing and the valve sleeve 30 moves tothe intermediate position in FIG. 2 against the action of a weakercompression spring 54, the pin 50 will move into contact with the bottom56 of the valve sleeve, as shown in the intermediate position of FIG. 2.

In this intermediate position, the piston body with the sealing ring 46has been moved from its starting position, shown in FIG. 1, and haspassed through a first region on one side of the closed gap 41 betweenthe end 36 of the valve sleeve and the seating 38, and through a secondregion to its position on the opposite side of the gap shown in FIG. 2.During this travel of the piston body past the closed gap, the sealingring is protected by the cylindrical surface 16 up to the gap, andthereafter by the sealing surface 14 of the valve sleeve.

During continued movement of the piston body from the intermediateposition shown in FIG. 2 to the open end position shown in FIG. 3, i.e.when the piston body is displaced into a third region, the pin 50 abutsthe bottom 56 of the valve sleeve and moves said valve sleeve, togetherwith the piston body, to the end position shown in FIG. 3, where thepiston body lies outside the end of the cylindrical sealing surface 16and the gap 41 is opened to form an open gap 41A (FIG. 3), whichincludes a through-flow gap 60, where the explosive, instantaneousthrough-flow of high-pressure oil takes place. The sealing ring 46,however, is well protected at a distance from this gap 60.

The inventive valve arrangement enables the valve to open immediately ata pressure of several hundred bars in the chamber 24, without risk ofdamaging the sealing ring 34.

The valve arrangement is closed in the reverse order, from the positionshown in FIG. 3 to the position shown in FIG. 1, the sealing ring 46being protected by the valve sleeve until the gap is closed and formsthe closed gap 41 (FIG. 2). It is only then that the sealing ring 46 ismoved past the closed gap 41 to its starting position, shown in FIG. 1.

When high pressure prevails solely in the chamber 24, and thus not inthe chamber 26, with the valve arrangement closed, it suffices toprovide the aforedescribed valve arrangement with only one single valvesleeve 28, with its associated functions, without taking furtherprotective measures. It is often necessary, however, to be able toalternate the high-pressure side, so that high pressure will prevail inthe chamber 26 but not in the chamber 24.

In order to provide for this alternative, a further sealing ring 64 madeof a substantially elastic material is disposed in a circular groove 66formed in the internal, cylindrical sealing surface 16 such as to sealagainst the outer cylindrical sealing surface 42 of the piston body 18.

A valve body 68 which includes a valve sleeve 70 and axially extendingchannels 72 is mounted for axial movement in the chamber 26. The outer,cylindrical sealing surface 74 of the valve sleeve forms an interruptedextension of the internal, cylindrical sealing surface 16. A channel 73which terminates at the closed gap 73 is located between the sleeve 70and the piston rod 48.

The valve body 68 has a conical end surface 76 which is intended to abutthe conical end surface 22 of the chamber when the piston body 18,together with the valve body 68, is displaced to the intermediateposition shown in FIG. 2. During this displacement, the valve body isbiased by a compression spring 80, such that the end 82 of the valvesleeve 70 will abut a seating 84 on an adjacent conical end of thepiston body 18, thereby to form a closed gap (FIGS. 1 and 2) between theend 82 of the valve sleeve and the seating 84 of the piston body.

When the piston body 18 is then moved from the intermediate positionshown in FIG. 2 to the open end position shown in FIG. 3, the valve body68 with the valve sleeve 70 will remain in abutment with the end surface22, so that the gap 86 is opened to form an open circular gap 86A (FIG.3), the end part of which is formed by the through-flow gap 60. Thesealing ring 64 is now located at a safe distance from the open gap 60and is protected effectively by the valve sleeve 70 when high-pressureoil flow through the gap 60.

FIGS. 4 and 5 illustrate respectively valve housings with mutuallydifferent configurations of the inventive valve arrangement. The valvehousing 90 in FIG. 4 forms a male part which can be inserted into afemale part formed by the valve housing 92 shown in FIG. 5. The male andfemale parts form the quick-coupling 93 illustrated in FIGS. 6 to 8.

The valve housing 90 has a connection 94 for connection to a conduit forhigh-pressure oil, and the valve housing 92 has a connection 96 forconnection to a conduit for high-pressure oil. In practice, only one orthe other of said connections will normally be connected to receivehigh-pressure oil, namely oil having a pressure of several hundred bars.

The male part or valve housing 90 can be mounted on a displaceablecarrier which is, for instance, manouvered hydraulically and advanced toa position in which a plurality of valve housings or female parts 92 aremoved forwards one after the other in positions for connection withrespective male parts. Alternatively the carrier can support a pluralityof male parts which can be coupled to a corresponding number of femaleparts mounted on a stationary carrier. The carrier holds the male andfemale parts in their mutually connected states, therewith obviating thenecessity of providing latching means of the kind necessary when saidparts are coupled together manually, e.g. in accordance with FIGS.12-14.

The flow passage located between the connection 94 and the coupling end98 of the valve housing 90 is configured along a part of its length as acylinder or an internal, cylindrical part 100, which discharges at oneend into the surrounding atmosphere and which is connected at its otherend to a widened part 102, which in turn adjoins a cylindrical pressurechamber 104.

Mounted for axial movement in the cylinder 100 is a piston body 106. Thepiston has an outer, cylindrical sealing surface 107 in which there isformed a circular groove 110 which accommodates an elastic sealing ring108. The piston body is carried by a piston rod 112 which is journalledin a valve body 114 for axial movement and which is held in theillustrated starting position by a weaker compression spring 116 mountedbetween a support surface 124A in the valve body 114 and the valve body106.

The valve body 114 is, in turn, journalled for axial movement in thechamber 104 and is held in the illustrated starting position by astronger compression spring 118, which biases the valve body intoabutment with an abutment surface 119 at the end of the chamber 104. Thespring 118 lies in a sleeve 117, one end of which forms a stop 117A forthe end 114A of the valve body 114. The valve body includes a pluralityof substantially axial channels 120, which connect the chamber 104 withthe widened part 102.

The valve body is configured with a valve sleeve 122, the internalsurface of which forms an internal, cylindrical sealing surface 124which forms an interrupted extension of the internal, cylindricalsealing surface 100 of the cylinder 100.

In the illustrated position, the end 126 of the valve sleeve abuts aseating 128 at the beginning of the widened part 102, while forming aclosed gap 130 with a given minimum leakage between the mutuallyabutting metal surfaces. In its open position shown in FIG. 4A, the gapis referenced 130A.

Formed between the valve sleeve 122 and the wall of the widened part 102is an annular gap which forms a channel 132 connecting the channels 120with the closed gap 130 and the open gap 130A respectively.

The valve housing, or the male part 90, has a cylindrical end-part 134which can be inserted into a corresponding, internally cylindrical part136 at the coupling end of the female part 92 of FIG. 5.

Provided in the female part 92 is a piston body 138 which includes anexternal, cylindrical sealing surface 139. The piston is attached to oneend of a piston rod 140, which is carried by an end-piece 142 in thepressure chamber 144 of the female part. The end-piece is held in itsend position by a stronger compression spring 146, the forwardly locatedend of which abuts a sealing sleeve 148, which, in turn, in a startingposition abuts an abutment surface 150 in the chamber.

The sealing sleeve 148 has an internal, cylindrical sealing surface 152against which a collar 154 guides and seals. The collar 154 is formed onthe rear end of a valve sleeve 156, the outer surface of which forms anexternal, cylindrical sealing surface 158, which, in turn, forms aninterrupted extension of the external, cylindrical sealing surface 160of the piston body.

The piston body 138 is guided in the sealing sleeve 148, in an internalcylindrical part thereof which forms a sealing surface 162 at theforward end of the sealing sleeve. The piston body coacts with anelastic sealing ring 164 disposed in a circular groove 166 provided inthe cylindrical sealing surface 162.

Also provided is an elastic sealing ring 168 which is accommodated in agroove provided in the forward, cylindrical part 136 of the chamber 144,for sealing against the sealing sleeve 148.

The end-piece 142 has provided therein axial channels 170 which connectthe chamber 144 with the connection 96 and which are connected to thechannel 145 disposed between the valve sleeve 156 and the piston rod 140and extending up to the closed gap 178. The valve sleeve 156 is biasedby a weaker spring 172, such that the forward end 174 of the valvesleeve abuts a seating 176 at the rear, conical end of the piston body.There is obtained between the end 174 and the seating 176 an openablegap which, in its closed position is referenced 178 in FIGS. 5, 6 and 7,and in its open position is referenced 178A in FIGS. 5A and 8respectively.

When the male part 90 is pressed against the female part 92, the pistonbody 132 of the female part remains in the illustrated position andforms a stop for the piston body 106 of the male part, the cylindricalend-part 134 of the male part being guided into the cylindrical part 136of the female part while pushing back the sealing sleeve 148 in a knownmanner, as illustrated in FIGS. 6, 7 and 8.

The quick-coupling 93 illustrated in FIGS. 6 to 8 can be used when ahigh pressure prevails in the chamber 104 of the male part and/or thechamber 144 of the female part.

As described above, the sealing ring 108 is moved relative to the closedgap 130 in a first region on one side of the gap to the end of a secondregion on the other side of the gap, as illustrated in FIGS. 4, 6 and 7.

At the same time, the sealing ring 164 is moved relative to the closedgap 178 in FIGS. 5, 6 and 7, in a first region on one side of the gap tothe end of a second region on the other side of the gap.

During the relative movement of the sealing rings 108 and 164respectively through the first and the second regions, the sealing ringis protected effectively against the effect of the high-pressure oil inone or the other of said chambers.

It is not until the sealing rings have left the second region and entera third region that opening of the two gaps commences, so as to formfully open gaps 130A and 178A respectively, these gaps merging with oneanother to form a flow passage for high-pressure oil in accordance withFIG. 8.

In the aforesaid third region, both of the sealing rings 108, 164 aremoved to an end position, together with associated valve sleeves 122 and156 respectively. In the illustration of FIGS. 4 and 4A, the piston body106 engages an abutment 124A at the end of the cylindrical surface 124,when the sealing ring 108 reaches the end of said second region,whereafter the piston body entrains or dogs the valve body 114, with itsvalve sleeve 122, along a path which corresponds to the distance betweenthe abutment 117A and the end 114A of the valve body, as seen in FIG. 4.This travel path from the position shown in FIG. 4A corresponds to thelength of the third region.

Similarly, the sealing surface 148 has an abutment surface 148A (FIGS. 5and 8) against which the collar 154 of the valve sleeve 156 abuts whenthe sealing ring 164 is brought, by relative displacement, to the end ofits second region of movement. Continued movement will cause the sealingring 164 to move in the third region, together with the valve sleeve156, until the inner end of the sealing sleeve lies in the vicinity ofthe end-piece 142, as shown in FIG. 8.

FIG. 9 illustrates a small modification of the valve housing 90, or themale part of FIG. 4, while FIG. 10 illustrates a corresponding smallmodification of the valve housing 92 or female part of FIG. 5. Thesemodifications are intended to facilitate manual coupling of said partswhen a relatively high residual-pressure remains in the male part, ascan sometimes occur in the case of certain hydraulic tools or machines,such as excavating machines and other types of loading machine ormachines. This residual pressure in the male part can offer someconsiderable resistance to manual coupling of the male part to thefemale part.

Those components of the embodiments shown in FIGS. 9 and 10 whichcorrespond to the components shown in FIGS. 4 and 5 are identified bythe same reference signs.

The male part is identified by the reference sign 90A and the femalepart by the reference sign 92B.

In FIG. 9, the piston body 106A is shown in its outer end position andcan be moved axially in the cylindrical part 100 against the action ofthe spring 116. The piston body is provided with two circular grooves,each of which accommodates a respective resilient sealing ring 108 and108A. The internal, cylindrical surface 124 of the valve body forms animpervious chamber 124B, which presents an abutment 124A at the bottomthereof, to form a stop for the piston body 106A in accordance with FIG.11, which shows the male part coupled to the female part.

When the valve arrangement is in its closed position, as illustrated inFIG. 9, the sealing rings 108 and 108A seal against the small amount ofoil which may possibly leak through the closed gap 130.

However, when pressing the piston body 106A into the valve sleeve 122,the sealing ring 108A will slide, with the minimum of friction, againstthe internal, cylindrical surface 124, which in practice results indeformation and minute leakage to the chamber 124B, although thisleakage is on a microscale. This leakage is considerable when couplingthe male part and female part together, since it causes a decrease inthe residual pressure in the chamber 104 of the male part, which in turnreduces the resistance to coupling said parts together.

A small leakage also occurs at the sealing ring 108 when coupling saidparts together, as the sealing ring slides along the cylindrical surface100.

The fluid which leaks to the chamber 124B, however, passes through oneor more channels 180 in the piston body 106A, to the forward end of thepiston body lying in abutment with the piston body 138 of the femalepart. This part has provided in the centre thereof a central, axialchannel 182 which discharges into the chamber 144 of the female part.

The outer end 184 of the channel 182 connects with the outer end of thechannel 180. The channel 182 is thereafter provided with a check valve,which has the form of a ball valve 186 biased by a spring 188, such thatflow can only occur in one direction, i.e. into the female part.

Fluid which leaks past the sealing ring 108 penetrates down between thepiston bodies to the channel end 184.

When coupling the male and female parts in the afore-described manner,the pressure in the chamber 144 of the female part will be considerablylower than the residual pressure in the chamber 104 of the male part.Because the residual pressure, which may at times be relatively high, islowered during the coupling operation, as a result of conducting thefluid leakage to the chamber 124B via the channels 180, 182, thehydraulic pressure acting on the piston body 106A is reduced, such as tofacilitate manual coupling of the male and female coupling-parts.

FIGS. 12 and 13 illustrate respectively a nipple or male part 190 and acoupling sleeve or female part 192, and FIG. 14 illustrates the malepart and the female part in a mutually coupled state, in which the twoparts are locked together by means of a ball catch 194.

The valve arrangement in the male part 190 is principally the same asthat illustrated in FIG. 4, whereas the female part 192 lacks theprovision of an inventive valve arrangement.

The piston body 106 of the male part, with sealing ring 108, coacts withthe valve sleeve 122 in the same manner as that described with referenceto FIG. 4.

For the purpose of facilitating manual coupling of the male part 190with the female part 192, the coupling-parts can be provided with anarrangement similar to that illustrated in FIGS. 9 and 10, for thepurpose of lowering the pressure in the chamber 104 while connectingsaid parts together. Prior to coupling said parts, a low pressureprevails in the chamber 96 of the female part.

We claim:
 1. A valve arrangement for a pressure fluid, such as apressure liquid, particularly high-pressure oil, comprising a valvehousing (10, 90, 190) through which there extends a flow passage whichis configured along part of its length with an internal, cylindricalsealing surface (16, 100, 160) which forms a guide for the outer,cylindrical sealing surface (42, 107, 162) of a piston body (18, 106,138), and in which arrangement there is provided in one of these sealingsurfaces a circular groove which accomodates a sealing ring (46, 64,108, 164) made of a substantially elastic material, and in which thepiston body is movable axially in relation to the other sealing surface,from a sealing starting position to an open position in which the pistonbody lies outside one end of said sealing surface and opens for throughflow, characterizedin that an axially, displaceable valve sleeve (30,70, 122, 156) is disposed coaxially with the two cylindrical sealingsurfaces (16, 42, 100, 107, 162, 160) and has a cylindricalvalve-sealing surface (40, 74, 124, 158) of essentially the samediameter as the two cylindrical sealing surfaces; in that the valvesleeve is biased by a spring (34, 80, 118, 172) such that one end (36,82, 126, 174) abuts substantially sealingly a seating (38, 86, 128, 176)at said end of said sealing surface such as to form a closed gap (41,86, 130, 178); in that said closed gap is situated at one end of achannel (32, 73, 132, 145), the other end of which is connected to aconnection part (12, 14, 94, 96) with a pressure-fluid source; in thatthe valve housing (10, 90, 190) is displaceable axially from a startingposition relative to the piston body (18, 106, 138) to an intermediateposition in which the sealing ring (46, 64, 108, 164) has been movedfrom a position on one side of the closed gap (41, 36, 130, 178) to aposition on the other side of said closed gap, and in that continueddisplacement of the valve housing (10, 90, 190) relative to the pistonbody causes the valve sleeve to be moved relative to the seating so asto open the gap and form an open through-flow gap (41A, 86A, 130A, 148A)between the seating and the end of the valve sleeve while the sealingring is protected by the valve sleeve at the same time.
 2. Anarrangement according to claim 1 in which the valve housing forms anipple or male part (90, 190) which is intended to be inserted into asleeve-like coupling part or female part (92, 192), the piston body(106, 106A) being movable axially from a forward end position in aninternal, cylindrical end-part (100) of the passage, in which the pistonbody seals with a sealing ring (108, 108A), to a rear end position, inwhich the piston body has been moved outside the cylindrical end-partand is located in a widened part of the passage, the thus obtained gapbetween the forward end of the piston body and the cylindrical end-partopening the passage through said male part, characterized in that theaxially movable valve sleeve (122) is disposed coaxially with thecylindrical end-part (100) and the forward end (126) of said valvesleeve is biased by a spring into substantially sealing abutment with aseating (128) located on the rear end of said cylindrical end-part, suchas to form a closed gap (130) which closes the end of a channel (132)extending along the outside of the valve sleeve to a pressure-fluidchamber (104) in the valve housing; in that the inner surface of thevalve sleeve forms an internal, cylindrical sealing surface (124) havingthe same radius as the external, cylindrical sealing surface (107) ofthe piston body (106); in that urging of the piston body to anintermediate position, said position being determined by engagement ofthe piston body with an abutment surface (124A) on the valve sleeve, iseffected against the action of a compression spring (116) duringmovement of the sealing ring (108, 108A) on the piston body from aposition on one side of the closed gap to a position on the other sideof the closed gap; and in that continued movement of the piston bodytowards said end position is operative to cause the piston body toentrain the valve sleeve and therewith open the closed gap to permitpressure fluid to flow through the valve arrangement.
 3. An arrangementaccording to claim 1, in which the valve housing forms a sleeve-likecoupling part or female part (92) for receiving a nipple or male part(90) by virtue of the fact that the end of the nipple forms a cylinderwhich can be pressed against a sealing sleeve (148) mounted for axialmovement in the female part and surrounding the piston body (138) heldaxially in the valve housing, such that the end-cylinder (134) of themale part is displaced inwards and over the piston body when couplingsaid parts together and forces back the sealing sleeve until the twomutually opposing piston bodies are located at a distance from the innerend of the internal, cylindrical part of the sealing sleeve such as toopen the through-flow passage, characterized in that an axiallydisplaceable valve sleeve (156) is displaced coaxially with the pistonbody (138) of the female part and abuts substantially sealingly at itsforward end with a seating (176) provided on the rear end of the pistonbody, such as to form a closed gap (174) at the end of a channel (145)which is connected with a connection (96) to a pressure-fluid source,the outer, cylindrical sealing surface (158) of the valve sleeve havingthe same diameter as the outer, cylindrical sealing surface (160) of thepiston body (138); in that the internal, cylindrical sealing surface(136) of the sealing sleeve is provided with a circular groove whichaccomodates the elastic sealing ring, in axially displacing the sealingsleeve in the valve housing to an intermediate position located betweena starting position and an inner, said ring end position is moved fromone side of the closed gap (178) to a position on the other side of saidgap; in that in said intermediate position the sealing sleeve is inabutment with a part (154) of the valve sleeve (156) such that continuedinward movement of the sealing sleeve (148) from said intermediateposition to the inward, end position will cause the sealing sleeve todisplace the valve sleeve (156) axially and therewith open the closedgap (178) to an open gap (178A) for through-flow of the pressure fluid.4. An arrangement according to claim 2, characterized in that the pistonbody (106A) of the male part (90) has two axially separated sealingrings (108, 108A) each of which is located on a respective side of theclosed gap (130) in the starting position of the piston body; in thatthe cylindrical chamber (124B) receiving the piston body is connectedwith the centre of the outer end of the piston body by means of at leastone through-passing channel (180) in the piston body; in that the pistonbody (138) of the female part (92) has a central, through-passingchannel (184, 182) which is provided with a check valve (186) and opensinto the pressure chamber (144) of the female part, such that thechannel (102) in the female part will receive leakage oil which, whenpressing-in the piston body (106A) of the male part, leaks past the onesealing ring (108A) and into the cylindrical chamber (124B) of the malepart, thereby lowering the pressure in the pressure chamber (104) of thesaid male part.